Single-roll grinding mill



Feb. 24, 1931.

A. E. M cALLuM SINGLE ROLL GRINDING MILL 2 Sheets-Sheet 1 Filed April 3, 1929 -Zizueaz $2 4/78 red Erwin w -egffregi'fiaa 'a-zzeam Feb. 24, 1931. A. E s. M cALLuM 1,794,235.

SINGLE ROLL GRINDING MILL Filed April 3, 1929 2 Sheets-Sheet 2 Patented Feb. 24, 1931 units PATENT Free SINGLE-ROLL GRINDING MILL Application filed April 3, 1929, Serial No. 352,265, and in Great Britain April 5, 1923.

This invention relates to grin-ding mills of the kind in which the material to be treated is fed from a hopper so as to pass between a grinding roller and a grinding bar or block arranged longitudinally of the roller. The object of the present invention is to provide improvements in the construction of mills of the kind above described, such improvements being designed to enable multiple grinding to be satisfactorily effected in a single roll mill. 7

According to the present invention a grinding mill having a grinning bar or block arranged longitudinally of a grinding roll is provided wherein a feed hopper disposed above the roll has a partition element so arranged tierein as to remove material which has passed between the grinding roll and bar and allow it to accumulate 0 until it overflows the partition onto the surface of the grinding roll. According to the preferred form of carrying the invention into efiect the partition element comprises a pivoted scraper blade extending throughout the length of the roll and hopper and this scraper blade may operate in conjunction with a fixed division plate which increases the space available for the accumulation of unground or partly ground material.

Reference will now be made to the accompanying drawings which illustrate by way of example constructions accorcing to the invention and in which Fig. 1 is a cross sectional elevation through a grinding roll and hopper,

Fig. 2 is a side elevation of the devices shown in Fig. 1 and Fig. 3 is a cross sectional elevation of a modified form of construction.

In the form shown in Figs. 1 and 2 blade a is pivot hopper 6 being carried upon a rod or spindle 0 extending above a grinding roll (5 and parallel to the axis of rotation thereof. The scraper blaoe a is disposed at the opposite side of the feed hopper b to that at which a grinding bar 6 is situated and when operative it occupies an inclined position with its lower edge directed towards the point at which the surface of the roll enters the hopper.

a scraper ally mounted within a feed The rod or spindle coon which the scraper blade is mounted is provided with a coiled springf one end of which bears against a fixed abutment g on the hopper base for normally maintaining the blade at in contact with the surface of the roll and externally of the hopper the rod 0 is provided with a handle it adapted to be engaged behind a retaining hook 2' attached to a fixed part j of the mill framework when the rod is partially rotated to bring the scraper blade a to the inoperative position indicated by broken lines in Fig. 1.

In operation material to be treated is fed from the hopper and passes between the grinding roll (Z and bar e in the usual manner. For the purposes of the present invention the usual scraping and delivery device is removed or rendered temporarily inoperative with the result that material passing between the grinding roll and bar adheres to the roll and re-enters the hopper in which it is re moved from the surface of the roll by the scraper blade a. The material thus removed accumulates between the scraper blade 4 and the adjacent wall of the hopper until it overflows on to the surface of the roll and again passes beneath the grinding bar. This procedure is repeated until the requisite degree of fineness has been reached andthe ground material is removed in the usual manner.

In'the form illustrated in Fig. 3 a'division plate'lc is employed extending throughout the length of the hopper b, the space between the lower edge of this plate hand the grinding roll (Z being" closed by a pivoted scraper blade Z which may be mounted and operated in the manner describedwith reference to Figs. 1 and 2. The object of this arrangement is to separate the ground from the unground material and in operation the part m of the hopper to the left of the scraper blade is filled with colour or other material to be ground and a shallower layer isplaced in the other division n on top of the grinding roll (Z. The capacitiesof the two parts of the hopper are'so calculated, that, as soon as the material in the division n passes under the grinding bar e it is carried round to the back of the machine into the space m where it sc ped. at the rollsby the blade increasing thereby the contents of the space m. This part of the hopper being full the introduction of additional material causes it to overflow and fall down into the space a where it becomes mixed with the material lying on the top of the roll. This process is continuous as long as multiple grinding is being carried out, that is to say, as long as the scraper blade Z is resting on the roll. WVhen it is considered that the material is ground sirfii'ciently the blade Z-is pivoted to the position shown in broken lines in Fig. 3 with the result that the wholeof the roll surface within the hopper is flooded inthe usual way and after the material has passed under the grinding bar it is taken off by the doctor and collected in the known manner.

I claim 1. A grinding mill, comprising a hopper, a grinding roll rotatable below said hopper, a grinding bar extending longitudinally of said grinding roll, and a partition element in -said hopper for removing from said grinding roll material which has passed between said grinding bar and roll and against which such material accumulates until it overflows into the adjacent portion of the hopper for redelivery to the grinding bar.

2. A single roll grinding mill comprising .a hopper, agrinding roll rotatable below said hopper, a grinding bar carried by said hopper and engaging said grinding roll. and a scraper blade in said hopper movable into and out of engagement with said grinding roll and operative when in engagement with said grinding roll-to remove partially ground material from the surface of the grinding roll for redelivery to the roll surface at another .point for further grinding.

3. A grinding mill according to claim 2 comprising resilient means normally urging the scraper blade into contact with the. grinding roll and means for securing the scraper blade out of contact with the grinding roll.

4. A grinding mill according to claim 1 wherein the partition element comprises a member of which the lower edge is spaced from the grinding roll anda scraper blade movable relatively to said member into and out of contact with the grinding roll, and means for holding said scraper bar out of contact with the grinding roll.

5. A grinding mill including a grinding roll, a feed hopper, a grinding bar extending longitudinally of the roll, a pivoted scraper plate disposed within the hopper, means for causing the scraper plate to act as a partition within the hopper and to remove material from the roll and redeliver it to the roll at another point for further vgrinding, the material ,beingadapted to overflow the PZLXlBltIOIL' 6. A grinding mill including a grinding roll, a feed hopper, a pivoted scraper plate disposed within the hopper, means for causing the scraper plate to act as a partition 

